Progress toward meaningful marine debris shoreline monitoring: Confronting the challenges of survey design in the United States

Few marine debris monitoring programs have explicitly applied statistical methods in their design, limiting data value and applicability. Here, we describe the NOAA Marine Debris Program's strategy for designing a scientifically robust monitoring survey in the United States to estimate shoreline debris status and trends. Key principles of experimental design are emphasized and applied across four phases: frame, design, monitor, implement and learn. Informed by a power analysis with spatially balanced site selection, the design includes 62 sites in each of 10 regions; 12 sites visited annually with quarterly replication and 50 sites visited once every five years (no within year replication), yielding reliable estimates of annual status and declining trends of 25% to 50% over an 11-year duration. This design may not be directly transferable, the underlying methodology can be tailored to suit alternative contexts. Practitioners should consider monitoring as a rigorous scientific endeavor to improve management value.